Liquid flow control device having improved surface for operative engagement with relatively moving paper machine forming wire



y 1966 c. w. E. WALKER 3,250,671

LIQUID FLOW CONTROL DEVICE HAVING IMPROVED SURFACE FOR OPERATIVEENGAGEMENT WITH RELATIVELY MOVING PAPER MACHINE FORMING WIRE Filed May7, 1965 INVENTOR. CZQ/ZJM/i/k/ a ATTORNEYS m xOOhw Ema-4a United StatesPatent 3,250,671 LIQUID FLOW CONTROL DEVICE HAVING IM- PROVED SURFACEFOR OPERATIVE ENGAGE- MENT WITH RELATIVELY MOVING PAPER MACHINE FORMINGWIRE Charles W. E. Walker, San Mateo, Calif., assignorto BeloitCorporation, Beloit, Wis., a corporation of Wisconsin Filed May 7, 1965,Ser. No. 454,145 11 Claims. (Cl. 162-374) This is a continuation-in-partof my application Serial No. 150,917, filed November 8, 1961, nowabandoned.

The instant invention relates to paper making machines, and moreparticularly to parts or elements of paper making machines which areadapted to contact the forming wire moving relative thereto.

In certain paper making machines, the stock or dilute suspension offibers is fed onto what is known as a forming wire which is actually afine mesh screen; and in the Fourdrinier type machine, the forming wireis often referred to as the Fourdrinier wire. In Fourdrinier typemachines, the forming wire has the structure of an endless loop of suchfine mesh screen which receives paper stock on the outer peripherythereof, dewatering such stock by movement of water through the screenand past initially the outer periphery and ultimately the innerperipheral surface of the looped screen, thereby ultimately forming amoist paper web on the loop outer peripheral surface (from which the webis removed for further processing in the machine at a later stage). Theforming wire travels at a relatively high speed in present-day papermachines, in the order of 1500 to 2500 feet per minute, and machines arebeing designed for. speeds of as much as 3000 feet per minute. Theforming wire, of course, comes into contact with ele ments such asrolls, which are rotating at a surface speed.

that is substantially the same as the speed of the traveling formingWire.

The forming wire also comes into contact with various elements in thepaper machine which are stationary or substantially so, to the extentthat there is significant relative movement between the travelingforming wire and such elements. These elements include primarily thesuction box covers, although the forming wire does move relative to andin contact with various other elements on the machine, including formingboards, deflector tops and deckle straps, all of which elements ordevices function to control liquid (i.e., water ordinarily) or stockflow in one way or another in a paper machine. The instant inventionprovides a novel structure for such elements which may come into contactwith the traveling forming wire, moving relative thereto. Such structurecomprises a suitable base or support material on which is securelymounted a layer of ceramic material, which ceramic material hasbeenfound to reduce the abrasive wear of the wire so as to increase the lifeof the wire. It will be appreciated that in the case of, for example,wooden suction box covers, the wire tends to wear away the covers, butin so doing the wire itself is subjected to abrasive wear, which iscompounded by the tendency for grit and other hard abrasive materials(known to be present in stock in fine particulate form) to becomeembedded in the wooden box tops and func tion as an abrasive withrespect to the wire.

The instant invention also provides a solid, smooth, mirror-finished,ceramic surface on such stationary element for contacting the solid wirethat affords sliding solid-against-solid type of frictional engagementbetween the moving wire and the stationary element, thus decreasing thepower consumption of the machine required to drive thewire.

azsasii Patented May 10, 1966 I instant ceramic layer-protected box topsdo not require this additional operational expense, because of theirreslstance to wear.

It is, therefore, an important object of the instant invention toprovide an improved element for a paper machine adapted to contact aforming wire moving relative thereto.

It is a further object of the instant invention to provide an improvedperforated paper machine suction box cover presenting a refractory,mirror-finished ceramic land surface for contact with a travelingforming wire surface moving relative thereto and urged thereagainst byvirtue of paper stock on the opposite wire surface being subjected to apressure differential to dewater such stock through the wire and box.

Other and further objects, features and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description thereof and the drawing attached heretoand made a part hereof. I

The drawing attached hereto is a sectional elevational view of a suctionbox mounted in association with the traveling forming wire and equippedwith the ceramic cover of the invention.

In the drawing, the reference numeral 10 indicates gen erally a suctionbox body of generally U-shaped cross section, which extends the fullwidth of the paper machine and, of course, the full width of the formingwire indicated at 11, traveling in the direction indicated by thearrowhead. The forming wire is shown herein only as a single line forsimplicity, although it will be appreciated that this forming wire 11 isa fine mesh screen, usually a metal screen which is the type of screenor wire that is used most advantageously withthe suction box of theinstant invention.

The suction box body 10 is provided with opposed generally parallelsupport members 12 and 12a which extend the full width of the machineacross the mouth 10a of the suction box body and present dove-tailgrooves 13 and 13a in opposed relation at the top of the suction boxbody 10. Slidably mountedin the dove-tail grooves 13, 13a is a metalplate 14 which has a tapered cross section along the edges 14a and 14bthereof to conform with the shape of the dove-tail grooves 13, 13a,respectively.

The metal plate 14 is perforated with drillings, slots or otherwise, butin the embodiment here shown the perforations are in the form ofdrillings 15a, 15b, 15c, etc., which form a myriad of perforationsthroughout the full width of the metal plate 14 for receiving watertherethrough, which is collected in the suction box body 10. The suctionbox body is, of course, maintained under a reduced pressure byconventional means which need not be describe-d in detail herein, andthe water collected therein is removed by conventional means such as adrop-leg or the like which also need not be described in detail herein.

The metal plate 14 functions as a base or supporting member whichcarries a ceramic layer 16 on the upper face thereof. The ceramic layerengages the ti'aveling forming wire 11 carrying thereon paper stockindicated generally at S. The forming wire 11 here shown is aFourdrinier forming wire in a conventional Fourdrinier machine; andthewire 11 moves at a relatively high rate of speed in the directionindicated by the arrow, whereas the suction box assembly, indicatedgenerally by the reference numeral A (and including the entire'body 10,the metal plate 14 and the ceramic coating 16, secured to the body 10via the supporting members 12, 12a) remains stationary.

Expressed in other terms, conventional to the paper machine builder, theFourdrinier type paper machine has a traveling looped forming wire 11with outer 11a and inner 11b peripheral forming wire surfaces and alsosuch machine is provided with means F for flowing a paper stock S ontothe outer peripheral surface 11a of the forming wire 11. Second means,i.e., the suction box shown at A and subsequent boxes indicateddiagrammatically at A A A A in the schematic view of the drawing, arepositioned within the loop of the wire 11 for moving Water from thestock S through the wire 11 from the outer 11a to and past the innerperipheral surface 11b thereof to dewater the stock and form a moistpaper web W on the wire 11 at the outer peripheral surface 11a thereofremote from such second means A, for dewatering; and the paper machineis also provided with third means indicated schematically in the drawingD D D and D; as drive rolls for effecting relative movement between thetraveling wire loop 11 and the aforesaid first means F and second meansA, A A etc., in the paper machine. It will also be appreciated that theaforesaid second means are indicated more specifically herein as atleast one box A defining a substantially regularly recurring pattern ofWater receiving apertures 15a, 15b, etc., therein maintaining a pressureditferential between the stock 8 on the wire loop outer periphery 11aand the wire loop inner periphery 11b for dewatering such stock S bywater movement in the previously described direction through the wire 11and into such water-receiving apertures 15a, 1517, etc. The box A isalso provided with land areas, indicated generally by the ceramic layer16 covering the metal layer 15, intermediate such water-receivingapertures 15a, 15b, etc., with such land areas 16 hearing against thewire loop inner periphery 11b and in control of direction of theaforesaid relative movement between the forming wire loop 11 and theaforesaid second means or box A for dewatering the stock 8, simply byvirtue of the fact that the suction box A engages the inner periphery11b of the wire 11 and thus controls its direction of movement to acertain extent. The engagement between the ceramic land areas 16 on thebox A and the inner periphery 11b of the wire is essentiallysolid-to-solid eugagement, as those skilled in the art will readilyrecognize and it is this type of engagement which has caused previousdifficulties in the operation of suction boxes in the prior art papermachines either by virtue of wearing of the wood covers on the suctionboxes or by virtue of grit being caused to imbed (and therefore score)the wooden box tops so that such grit in fine particulate form willfunction as an abrasive with respect to the wire, or wearing may resultfrom both causes, so that both the wire and the suction box top mustultimately be replaced more often than is desirable. In the practice ofthe instant-invention the suction box top or land areas 16 which engagethe inner periphery 11b of the wire 11 consists substantially entirelyof the mirror-finished refractory monolithic ceramic material which isdescribed hereinbefore as being resistant to Wear per se and alsoresistant to the previously mentioned cause of wear or abrasion on thewire, namely, the imbedding of the grit particles in the imbedding ofthe grit particles in the suction box top. In other words, the ceramicland areas 16 are inherently resistant to wearing by the relativelysofter metal wire as well as wearing by the grit particles which areknown to be comparatively hard inorganic and even ceramic materials, forthe reason that the land areas 16 are mirrorfinished refractorymonolithic hard ceramic layers or bodies of the materials described inthis specification which have inherently the aforesaid properties withrespect to being hard, refractory, crystalline, monolithic, and thelike. The additional feature of being mirror-finished is significant,however, because it is known by those skilled in solid-to-solid frictionthat when two solids are moved in engagement with each other andrelative to each other the harder solid will abrade the softer solid,

unless and only unless the harder solid is formed with a surface suchthat it will not abrade the softer solid. In this particular instancethe harder solid is the ceramic mirror-finished land areas 16 and it is,of course, inherent ly much harder than the metallic wire, aspaper-machine builders will readily recognize from knowledge of metallicforming wires and an examination of the Bradstreet patent specificallyreferred to hereinafter and the ma terials described therein. Theskilled worker in the art will also recognize that the materialsdescribed in the Bradstreet patent have at least substantially thehardness of the grit particles which are generally understood to besilicon carbide or similar hard materials that break loose from the pulpmaking machinery and thus become incorported in the stock at an earlystage in the production of the stock and are carried along with thestock to the forming wire 11 in conventional paper making.

Although specific aspects of the ceramic material or layer 16 will bedescribed in detail hereinafter, it is sufficient to note first that theceramic layer 16 is secured to the base plate 14 and, as here shown,conforms substantially with the top shape thereof, i.e., the layer 16 isse cured to land areas only on the plate 14 and leaves the perforations15a, 15b, etc., open. In this respect, it will be noted that at theoncoming top edge 16a, the ceramic coating is curved so as to present asmoothly curved surface, as contrasted to a sharp edge. Likewise, thetrailing edge 16b of the ceramic layer 16 is curved so as to present arounded smooth edge, rather than a sharp edge. The rounded edges 16a,16b, and particularly, the rounded edge 16a at the oncoming side of thewire 11 affords a very great advantage in minimizing wear on the wirewhen it initially comes into contact with the ceramic top 16 for thesuction box A. Actually, the ceramic coating or layer 16 is preferablyapplied to the base plate 14 in a relatively thin layer of about of aninch (ranging preferably from about 0.02 inch to about 0.1 inch) so asto conform substantially with the overall shape of the top of the metalsupport 14, which is also provided with rounded edges at the oncomingand offrunning top side. The ceramic coating is preferably applied Withheat, so that there is sintering or fusion at least at the surface ofthe ceramic particles and the same are sintered together and onto themetal supporting plate 14. After such application of ceramic particlesby heat to effect the formation of a monolithic layer 16 secured to thetop of the metal plate 14, it has been found particularly advantageousto polish the exposed wire-contact ing top surface of the ceramic layer16 to obtain a mirror finish thereon,

The application of the ceramic coating to the metal layer 14 ispreferably carried out by spraying the metal Support 14 with a suitablerefractory metallic oxide using a high temperature spray gun with anoxyacetylene or oxyhydrogen flame; and it has been found that chromeoxide is particularly satisfactory for this purpose. After the ceramiccoating has been so applied to the surface of the metal plate 14, it mayoften be desirable to give the ceramic layer 16 a subsequent or moreprolonged heat treatment to effect more complete fusion and integrationof the layer 16, to minimize porosity therein.

A particularly satisfactory method of applying the ceramic coating 16 tothe surface of the metal plate 14 is described in detail in BradstreetUS. Patent No. 2,904,449, the disclosure of which is incorporated hereinby reference. The ceramic materials employed in the practice of theinvention, using the method of said Patent No. 2,904,449, are, ofcourse, water insoluble inorganic crystalline materials which have arelatively high melting or softening point. Preferably the materialsused are refractory at about 1000 to 1200" C.

The ceramic materials which may be used in the practice of the instantinvention include all of those specifically referred to in said PatentNo. 2,904,449, which include ilmenite, rutile, kyanite, sillimanite,bauxite and zircon. Alumina and chromia may also be used to particularadvantage.

For example, using a procedure of Example II of said Patent No.2,904,449, for the application of a 50 to 60 mil coating of flamesprayed mullite, one obtains an excellent ceramic layer 16 on the metalbase support 14.

The resulting material is polished to a mirror finish. Such flamespraying process, of course, does not involve filling or plugging of thevarious perforations 15a, 15b, 150 in the metal support 14, so that thefunction of the suction box top 14-16 is retained.

The procedure of the previous paragraph is repeated using, instead ofmullite, powdered chromia and the resulting ceramic coated suction boxtop 14, 16 is found to be particularly suitable for use in the practiceof the instant invention.

It will be understood that modifications and variations may be effectedwithout departing from the spirit and scope of the novel concepts of.the present invention.

I claim as my invention:

1. A suction box cover for Fourdrinier machines comprising a perforatedcover for the suction box and in contact with which is moved theFourdrinier screen wire, said cover comprising a perforated base memberand a screen wire contacting body consisting essentially of a layer ofcrystalline refractory metal oxide ceramic'material secured'to saidperforated base member, said ceramic material presenting a smooth mirrorfinish surface to said wire.

2. A paper machine suction box cover adapted to contact a forming wiremoving relative thereto comprising a base member and a cover thereforand secured thereto, said cover having perforations and land areas, theimprovement in said cover consisting essentially of a layer of ceramicmaterial refractory at 1000 C. on said cover presenting a smooth, mirrorfinish surface of said ceramic material for contact with said formingwire, said cover having a generally smooth transverse forward edgeconverging gradually with the moving wire passing over said edge andthen over the cover body, said layer of ceramic material being fused tothe land areas including said smooth forward edge of said cover andleaving the perforations open.

3. A perforated paper machine suction box cover comprising a basesupport having a myriad of perforations with land areas therebetween anda ceramic layer fused only to the land areas thereof, said ceramic layerpresenting a smooth mirror finish surface for contact with a travelingforming wire moving relative thereto, and said layer being formed ofmonolithic hard crystalline metal oxide refractory at 1000 C.

4. In a paper machine having a rapidly traveling forming wire of finemesh metal screen for receiving and deedge consisting of a ceramicmaterial smoothed to a mirror finish to facilitate sliding frictionalengagement with the forming wire'and refractory at 1000 C. so as to bewear-resistant with respect to the wire as 'well as grit and otherforeign material.

5. In a paper machine having a rapidly traveling forming wire of finemesh metal screen for receiving and dewatering stock thereon, adewatering device consisting essentially of first means presenting tothe traveling wire a transverse monolithic surface layer for contacttherewith having a' smoothly curved leading transverse edge on the sideof the surface from which the wire approaches, second means mounting thefirst means for movement of the wire relative to said surface presentedthereby, and third means connected to said first means for drawing watertoward said first means fromthe stock and through such wire to assist instock dewatering, said transverse monolithic surface layer with itssmoothly curved leading edge consisting of a ceramic crystallinerefractory metal oxide polished to a mirror finish to facilitate slidingfrictional engagement with the forming wire and wear-resistance withrespect to the wire as well as grit and other foreign material.

6. In a paper machine having a rapidly traveling form-' ing wire of finemesh metal screen for receiving and dewatering stock thereon, adewatering device consisting essentially of first means presenting tothe traveling wire a transverse thin monolithic surface layer forcontact there with, said layer being secured to a structural substratematerial and having a smoothly curved leading transverse edge on theside of the surface from which the wire approaches, second meansmounting the first means for movement of the wire relative to saidsurface presented thereby, and third means connected to said first meansfor drawing water toward said first means from the stock and throughsuch wire to assist in stock dewatering, said transverse monolithicsurface layer with its smoothly curved leading edge consisting of aceramic material smoothed to a mirror finish to facilitate slidingfrictionalengagement with the'forming wire and refractory at 1000 C. soas to be wear-resistant with respect to the wire as well as grit andother foreign material.

7. In a paper machine having a rapidly traveling forming wire of finemesh metal screen for receiving and deand through such wire to assist instock dewatering,

said transverse monolithic surface layer with its smoothly curvedleading edge consisting of a ceramic crystalline refractory metal oxidepolished to a mirror finish to facilitate sliding frictional engagementwith the forming wire and wear-resistance with respect to the wire aswell as grit and other foreign material.

8. In a paper machine having a rapidly traveling forming wire of finemesh metal screen for receiving and dewatering stock thereon, adewatering device consisting essentially of first means presenting tothe traveling wire a transverse thin monolithic surface layer forcontact therewith, said layer being secured to a structural metalsubstrate material and having a smoothly curved leading transverse edgeon the side of the surface from which the wire approaches, second meansmounting the first means for movement of the wire relative to saidsurface presented thereby, and third means connected to said first meansfor drawing water toward said first means from thestock and through suchwire to assist in stock dewatering, said transverse monolithic surfacelayer with its smoothly curved leading edge consisting of a ceramicmaterial smoothed to a mirror finish to facilitate sliding frictionalengagement with the forming wire and refractory at 1000 C. so as to bewear-resistant with respect to the wire as well as grit and otherforeign material. I

9. In a paper machine having a rapidly traveling forming wire of finemesh metal screen for receiving and dewatering stock thereon, adewatering device consisting essentially of first means presenting tothe traveling wire a thin transverse monolithic surface layer forcontact therewith, said layer being bonded to a structural metalsubstrate and having a smoothly curved leading transverse edge on theside of the surface from which the wire approaches, second meansmounting the first means for movement of the wire relative to saidsurface presented thereby, and third means connected to said first meansfor drawing water toward said first means from the stock and throughsuch wire to assist in stock dewatering, said transverse monolithicsurface layer with its smoothly curved leading edge consisting of aceramic crystalline refractory metal oxide polished to a mirror finishto facilitate sliding frictional engagement with the forming wire andwear-resistance with respect to the wire as well as grit and otherforeign material.

10. In a paper making machine having a traveling looped forming wirewith outer and inner peripheral forming wire surfaces and also providedwith means for flowing a paper stock onto the outer peripheral surfacethereof, second means within the wire loop for moving water from suchstock through the wire from the outer to and past the inner peripheralsurface thereof to dewater the stock and form a moist paper web on thewire outer peripheral surface, and third means for effecting. relativemovement between said traveling wire loop and the aforesaid first andsecond means in said paper machine, the improvement characterized by astructure for said second means comprising at least one box defining asubstantially regularly recurring pattern of water-receiving aperturestherein maintaining a pressure differential between stock on the wireloop outer periphery and the wire inner periphery for such stockdewatering by water movement in the direction aforesaid into saidwater-receiving apertures, said box being provided with land areasintermediate such water-receiving apertures bearing against the wireloop inner periphery in control of direction of the aforesaid relativemovement between the forming wire loop and the aforesaid second meansfor dewatering the stock, said land areas presenting to and bearingagainst the wire loop inner periphery, for essentially solid-to-solidengagement,

a mirror finished refractory monolithic hard crystalline metal oxideceramic body, that is resistant to wear by the comparatively softermetallic forming wire screen and also resistant to wear by inherentlypresent inorganic particulate ceramic grit particles in the stock whichmay be carried over the surface-of such body by the forming wire in thecourse of dewatering the stock and operation of the machine.

11. In a paper making machine having a traveling looped forming wirewith outer and inner peripheral forming wire surfaces and also providedwith means for flowing a paper stock onto the outer peripheral surfacethereof, second means within the wire loop for moving water from suchstock through the wire from the outer to and past the inner peripheralsurface thereof to dewater the stock and form a moist paper web on thewire outer peripheral surface, and third means foreifecting relativemovement between said traveling wire loop and the aforesaid first andsecond means in said paper machine, the improvement characterized by astructure for said second means comprising at least one elementextending in the cross machine direction and defining both solid surfaceand water-receiving aperture means maintaining a pressure differentialbetween stock on the wire loop outer periphery and the wire innerperiphery for such stock dewatering by water movement in the directionaforesaid into said water-receiving aper- V tures, said element beingprovided with land areas immediately adjacent such aperture meansbearing against the wire loop inner periphery in control of direction ofthe aforesaid relative movement between the forming wire loop and theaforesaid second means and said land areas presenting to and bearingagainst the wire loop inner periphery, for essentially solid-to-solidengagement, a mirror finished monolithic hard ceramic body refractory at1000 C., that is resistant to wear by the comparatively softer metallicforming wire screen and also resistant to wear by inherently presentinorganic particulate ceramic grit particles in the stock which may becarried over the surface of such body by the forming wire in the courseof dewatering the stock and operation of the machine.

References Cited by the Examiner UNITED STATES PATENTS 1,703,010 2/1929Manson 162374 2,173,484 9/ 1939 Lerch et al 117-16 2,712,776 7/ 1955Wagenknecht 162374 2,904,449 9/1959 Bradstreet 1l7105.2 3,067,81612/1962 Gould 162374 DONALL H. SYLVESTER, Primary Examiner.

I. H. NEWSOME, Assistant Examiner.

1. A SUCTION BOX COVER FOR FOURDRINIER MACHINES COMPRISING A PERFORATEDCOVER FOR THE SUCTION BOX AND IN COMTACT WITH WHICH IS MOVED THEFOURDRINIER SCREEN WIRE, SAID COVER COMPRISING A PERFORATED BASE MEMBERAND A SCREEN WIRE CONTACTING BODY CONSISTING ESSENTIALLY OF A LAYER OFCRYSTALLINE REFRACTORY METAL OXIDE CERAMIC MATERIAL SECURED TO SAIDPERFORATED BASE MEMBER, SAID CERAMIC MATERIAL PRESENTING A SMOOTH MIRRORFINISH SURFACE TO SAID WIRE.